The present invention relates to a linkage assembly for use with a boom of a skid steer loader that controls the path of the pivot attachment point between the boom and a bucket or other implement to permit reaching a greater height and providing for a substantially vertical path for the lower portion of boom travel and a forward movement of the attachment point relative to the loader frame in the upper portions of the path of travel of the boom.
The U.S. Pat. No. 5,169,278 discloses a vertical lift loader boom that has a control linkage that guides movement of the outer end of the boom as it is raised and lowered. The control linkage is arranged to provide a generally vertical path of movement, and fits onto existing loader frames.
The present invention provides for a linkage that ensures a high lift with a forward movement of the bucket, particularly in the upper one-third of the path of movement, and with the maximum forward movement at or near the maximum height of the boom.
The present invention relates to a loader boom system that has a control linkage that includes selected lengths and arrangement of the control links so that as a hydraulic actuator moves the boom upwardly, the forward end of the boom, where the boom attaches to a bucket or other tool, moves substantially vertically and slightly forwardly until the boom reaches in the range of the upper one-third of its travel. Then, the outer end of the boom moves forwardly in order to reach a location that is being used for dumping. The boom has a main boom portion, that is pivoted to boom supports on the loader structure through an articulated boom support link that is elongated in vertical direction. A control link is attached at one end to the boom at a desired location, and attached to the loader frame or boom support frame adjacent to the axle point of the loader at an opposite end. The control link is elongated, to provide for control of the advanced boom path, as the boom is lifted, the control link causes the articulated boom support link to pivot substantially rearwardly as the boom is initially raised, and then incline forwardly, with maximum forward inclination at the uppermost travel of the boom.
The disclosed linkage arrangement provides the ability to raise a load and move it forwardly relative to loader frame at the upper portion of boom operation to increase the ease of loading, and yet. have a substantially vertical path in the lower two-thirds or so of its path.